Change SkImageDecoders to take an SkStreamRewindable.

src/images/SkImageRef_ashmem.cpp

Index: src/images/SkImageRef_ashmem.cpp
diff --git a/src/images/SkImageRef_ashmem.cpp b/src/images/SkImageRef_ashmem.cpp
index a4058ff6d77b0d42581194c9bdfa89989788655a..0186bf6a55f89f980cb1a7070308e35a5beedee1 100644
--- a/src/images/SkImageRef_ashmem.cpp
+++ b/src/images/SkImageRef_ashmem.cpp
@@ -31,7 +31,7 @@ static size_t roundToPageSize(size_t size) {
     return newsize;
 }
 
-SkImageRef_ashmem::SkImageRef_ashmem(SkStream* stream,
+SkImageRef_ashmem::SkImageRef_ashmem(SkStreamRewindable* stream,
                                              SkBitmap::Config config,
                                              int sampleSize)
         : SkImageRef(stream, config, sampleSize) {
@@ -126,7 +126,7 @@ private:
     const char*  fName;
 };
 
-bool SkImageRef_ashmem::onDecode(SkImageDecoder* codec, SkStream* stream,
+bool SkImageRef_ashmem::onDecode(SkImageDecoder* codec, SkStreamRewindable* stream,
                                  SkBitmap* bitmap, SkBitmap::Config config,
                                  SkImageDecoder::Mode mode) {